MIZUMAKI, Fukuoka -- A 57-year-old man died after being bitten on the throat by a Tosa dog he had kept at his home here, police said.

The victim, 57-year-old Tadashi Naganuma, was found collapsed in the cage at his home in Mizumaki at about 8:45 a.m. on Monday. His 81-year-old father, who entered the cage to try to help him, was also bitten on the face and arm.

Two construction workers in the area who noticed the commotion, retrieved Naganuma and his father from the cage, but Naganuma who had been bitten on the throat, died. His father suffered serious injuries, while the two workers were lightly injured.

Naganuma's cause of death was traumatic shock. He had reportedly been bitten in several places over his body. Based on the condition of his body, officials said there was a possibility that he had been bitten several hours before he was found. Police are investigating the situation at Naganuma's home at the time.

Fukuoka Prefectural Police said that the dog was a four-year-old male. It stood about 1 meter tall, had body length of about 1.2 meters, and weighed about 50 kilograms. It was registered with a health center in about 2004. The cage the dog had been kept in measured about 3.5 meters by 4.5 meters. Tosa dogs are known as a fighting breed.